Send Unlimited Emails Per Day: RackNerd VPS + Mail-in-a-Box Setup

So you want to run your own email server without hitting send limits every single day? That's actually doable—and surprisingly straightforward if you pick the right VPS provider. RackNerd keeps port 25 open by default, which means you can send outbound emails without artificial caps strangling your operations. Pair that with Mail-in-a-Box (a free, open-source setup tool), and you've got yourself a proper email server running on Ubuntu in less time than it takes to argue with Gmail's rate limits.

Why Bother With Your Own Email Server?

Look, most shared hosting and mainstream email services will slap a daily sending limit on you faster than you can say "bulk newsletter." Sometimes it's 100 emails per day, sometimes 500—but it's always something. If you're running any kind of outreach campaign, transactional emails for a SaaS product, or just need reliable control over your email infrastructure, those limits become a headache real fast.

RackNerd VPS changes that equation. Port 25 is open out of the box, no begging support tickets required. You're basically free to send as much as your server and IP reputation can handle. The trick is doing it responsibly—because unlimited sending doesn't mean you should blast away like a spammer. Warm up your IP, build trust with receiving servers, and you'll have a setup that actually delivers to inboxes instead of spam folders.

What You'll Need

Mail-in-a-Box isn't demanding, but it does have a few baseline requirements:

• Ubuntu 22.04 LTS (the only officially supported OS)

• At least 1GB RAM (though 2GB is smarter if you plan to handle real volume)

• 1 vCore minimum

• A domain name you control (you'll need to set DNS records)

• A VPS with port 25 open (that's where RackNerd shines)

The whole thing is free and open-source, which is nice. No licensing fees, no upsells—just a clean web interface for managing your mail server once it's running.

Step 1: Grab a RackNerd VPS

First things first—get yourself a VPS. RackNerd has ridiculously cheap annual plans that make this whole experiment affordable even if you're just testing the waters. The $22.99/year tier (works out to about $1.92/month) is plenty to start with if you're sending moderate volume. Need more horsepower? The 4GB plan at $38.88/year gives you more breathing room for larger email lists.

Pick a data center location that makes sense for your audience. If you're targeting Europe, the France location works. US-based? Go with one of their domestic options. The location matters a bit for latency and how receiving mail servers perceive your IP, but honestly, it's not a dealbreaker either way.

Once you've signed up and provisioned your server, you'll get an IP address and root credentials. Hang onto those—you'll need them in about 30 seconds.

Step 2: Point Your Domain at the VPS

Before you do anything with Mail-in-a-Box, set up DNS records for your domain. You need:

• An A record pointing your domain (and the box subdomain) to your VPS IP

• An MX record pointing to box.yourdomain.com (priority 10 is standard)

If you're using Namecheap or any other registrar, this is straightforward—just log into your DNS settings and add the records. Give it a few minutes to propagate before moving forward. DNS can be slow sometimes, but it's better to wait than to troubleshoot confusing errors later.

Step 3: SSH Into Your Server

Fire up your SSH client—Bitvise works great on Windows, or just use Terminal if you're on Mac/Linux. Connect to your VPS using the IP address and root credentials RackNerd gave you.

Once you're in, update your system packages so you're not running outdated software:

sudo apt update && sudo apt upgrade -y

This takes a minute or two. Grab a coffee, stretch, whatever. When it's done, you're ready to install Mail-in-a-Box.

Step 4: Install Mail-in-a-Box

Here's where it gets absurdly simple. Mail-in-a-Box has a one-line installer. Run this:

curl -s https://mailinabox.email/setup.sh | sudo bash

The script kicks off and starts asking questions. It'll want to know:

• Your primary email address (like admin@yourdomain.com)

• The hostname for your box (usually box.yourdomain.com)

• A timezone for the server

Answer those, and then the installer goes to work. It installs and configures Postfix, Dovecot, Nginx, DNS services, spam filtering with SpamAssassin, and a bunch of other components you'd normally spend hours setting up manually. The whole process takes maybe 10-15 minutes depending on your VPS speed.

When it finishes, you'll see a message with a URL to access the Mail-in-a-Box admin panel. Bookmark that. You'll also get a randomly generated admin password—write it down or change it immediately.

Step 5: Lock Down DNS and Check Your Setup

Log into the Mail-in-a-Box admin panel using the URL and credentials from the install. The first thing you'll notice is a big "System Status Checks" section. This is where Mail-in-a-Box tells you what's working and what needs attention.

Most likely, you'll see warnings about DNS records. That's normal—Mail-in-a-Box wants you to copy specific DNS entries (SPF, DKIM, DMARC, etc.) into your domain registrar's DNS settings. These records prove to other mail servers that you're legit and not some random spammer.

Copy the records exactly as shown, paste them into your DNS provider, and wait for propagation. Check back in the admin panel after 10-20 minutes. Once everything shows green checkmarks, you're golden.

Step 6: Create Email Accounts and Test

In the admin panel, go to "Mail" → "Users" and create an email account. Set a strong password—this is going out on the public internet, after all.

Now test it. Use Thunderbird (or any email client) to connect to your new mail server. Set it up with IMAP/SMTP using the settings Mail-in-a-Box provides. Send yourself a test email from Gmail or another provider, then reply from your new server.

If that works, send an email to mail-tester.com—it's a free service that scores your email setup and tells you if anything's misconfigured. You want at least an 8/10, ideally 10/10. If your score's lower, check the report for specific issues (usually DNS or reverse DNS problems).

Step 7: Warm Up Your IP Address

Here's the part nobody tells you until it's too late: a brand-new IP address has zero reputation with major email providers. If you start blasting 10,000 emails on day one, you're going to land in spam folders—or get your IP blacklisted entirely.

Start slow. Send maybe 50-100 emails the first day, then gradually increase volume over a couple weeks. This builds trust with Gmail, Outlook, Yahoo, and other big receivers. They see consistent, reasonable sending patterns and start treating your emails like legitimate mail instead of spam.

👉 Need a reliable VPS with open port 25 and no artificial sending limits? RackNerd's got you covered

Step 8: Monitor and Maintain

Check your Mail-in-a-Box admin panel regularly. It'll alert you to system updates, certificate renewals, and any issues that pop up. Keep your server updated—run apt update && apt upgrade every week or two.

Watch your mail logs if you're troubleshooting delivery issues. They live in /var/log/mail.log and can tell you exactly why an email bounced or got rejected.

Also, keep an eye on blacklists. Services like MXToolbox let you check if your IP has been flagged. If it happens (and it might, especially early on), don't panic—most blacklists let you request removal once you've fixed whatever caused the issue.

Common Mistakes to Avoid

Skipping DNS records. If your SPF, DKIM, and DMARC aren't set up correctly, your emails will get rejected or marked as spam. Double-check everything in your DNS settings.

Ignoring reverse DNS. Your VPS provider (RackNerd in this case) needs to set the reverse DNS (PTR record) for your IP to match your mail server's hostname. Open a support ticket if it's not already configured.

Sending too much too fast. Seriously, warm up your IP. There's no shortcut here. Patience pays off in the long run.

Using a sketchy domain. If your domain is brand-new or has a spammy history, you're starting from behind. Use a clean domain that's been registered for a while.

What About Alternatives?

If you want to compare, here are a few other VPS providers that keep port 25 open:

• Contabo limits you to 25 emails per minute (still decent for smaller operations)

• KnownHost allows 60 emails per minute (solid middle ground)

• Hostinger only permits 5 emails per minute (pretty restrictive)

RackNerd doesn't impose per-minute caps, which gives you more flexibility. For the price and the lack of artificial throttling, it's hard to beat if you're serious about running your own mail server.

Other Email Server Options

Mail-in-a-Box isn't the only game in town. If you want to explore alternatives:

• aaPanel with Mail Server plugin (more manual setup)

• HestiaCP (decent control panel with built-in mail)

• FastPanel (newer, but getting popular)

• CyberPanel (heavy on features, lighter on resources than some)

• Cloudron (focuses on app management, including email)

Each has trade-offs. Mail-in-a-Box wins on simplicity and "just works" factor. The others give you more control at the cost of complexity.

Wrapping Up

Running your own email server isn't some arcane black magic anymore. With RackNerd VPS and Mail-in-a-Box, you can have a fully functional mail server running in under an hour. You get control, flexibility, and no arbitrary sending limits—just make sure you play by the rules (warm up that IP, configure DNS properly, monitor your reputation).

If you've been frustrated with third-party email service caps or just want to understand how email infrastructure actually works, this is a solid project to dive into. 👉 Grab a RackNerd VPS and see what unlimited sending on your own terms actually feels like. Build it right, warm it up properly, and you'll have a reliable email server that does exactly what you need without asking permission every time you hit send.